Electric switch



Dec. 18, v1928.

l B. E. 'GETC'HLL 'lwJTRIc swITcH"4 Filed' April 25, '1924 I. 2--sngetslsneent-2 Y Patented Dec. 18, 1928.

UNITED STATES l v1 ,9s9se PATENT OFFICE.

BENJAMIN E. GETCHELL, OF PLAINVILLE, CONNECTICUT, ASSIGNOR- TO THE TRUM- BULL ELECTRIC MANUFACTURING COMPANY, OF

CORPORATION OF CONNECTICUT.

PLAINVILLE, CONNECTICUT, A

ELECTRIC SWITCH.

Application filed April 23, 1924. Serial No. 708,355.

My invention relates particularlyito what is commonly ltermed a motor starting switch. My former Patent, No. 1,477,871,

of D ec. 18, 1923, shows a switch of the same general type. My former patent, however,

shows a construction particularl adapted in detail lto a 3-wire system, w ereas my present invention is particularly directed to a switch for use with a tour-wire system.

rugged and reliable construction of this type which may be opened and closed by hand,

but whichvis adapted to open the circuit autol'natieallyA upon undue variations in the loadin any leg of the circuit. l f

Because of the fact that there is no difterence in voltage between the phases of 2- phase circuits, the under-voltage release coil will not operate if connected between the over-load relays of the'two phases. It be comes necessary, therefore, to employ 2 coils,

one in each phase. The special object of my invention is to' design an apparatus of this character so that the same type coil construc-V tion may be used with each phase..

r I accordingly employ two separate electromagnets, one connected across each phase through the overload relay. The main switch is controllable. by manually-operable means for opening and closing the circuit and a spring for automatically opening the circuit. One of the magnets normally holds the switch in a closed posit-ion and the other magnet controls a supplementary switch which is in circuit with the coil of the first magnet. The over-load relays are preferably of the closed contact type, such, for instance, as more fully setforth in my Patent 1,569,364, dated January 12, 1926. I have constructed the parts so that the supple mentary switch can be adjusted for voltage trip in asimple manner.

Fig. 1 is aperspectiwfe view of a-construction embodying the improvements of mylinvcntion` th(` switch being shown in the normal closed circuit operating position.

Fig. 2 is a diagrammatic plan view showing the circuits. 4

Fig. 3 is a side viewv of one of the concontrolled thereby.

Fig. 4 is an edge view and section of the contacts ot the supplemental switch ot' Fig. 3;

The switch is provided with upper cir- The main object is to provide a simple but trol magnets and the supplementary switch,

cuit terminals 5, (i1 and 7, 8 for the respective phases, and with lower terminals 9, 10 and 11, 12. Movable switch members, for instance of knife blade type 13, 14, 15, 16 arerprovided for opening and closing the lines. These blades are preferably hinged at. the lower` ends, as at 17, 18 and 19, 20. The upper ends of the blades 4 are connected by an insulating crossbar 21,' which isprovided with hook or looplike members 22 having a lost motion .connection with the operating crank 23, which is adapted to be operated byhand inthe usual manner. vThe cross-bar 21 is also connected to the crank 23 by springs 24 for accentuating the opening movement of t-he switch. The crank 23 is also connected to a stationary` element for instance a wall of the box by a spring 25, which tends ltofmove the: crank 23and` the switch blades to an open circuit position.

Over-load relay devices such as 26,27 are provided for the two phases. The relay 26 has a heating coil 28 connecting the station ary terminals 17,and 9. The intermediate relay clip member 29 is normally electrically connected to the terminal 9 through thc bi. metallic thermostatic arm 30 and the contact screw .31.

vThe magnet coil 32 is connectedv across the first phase between the terminals 2) and 18 and provided With an armature 33 which is pivoted at 34. This' armature is connected to the operating crank 23 by means of the bar which has a sliding. engagement at its lower end with the pin 36 carried by the armature. The bar is provided with a slot 37 to permit it to move with respect to the pin 36. Roller 38 carried by thel armature normally serves as an `abutment for the lower cnd of the bar 35. lVhcn the magnet 32 is energized thevparts are held inthe position shown in Figure 1 as more fully described in my `former Patent No.

The relay 27 may be constructed exactly vlike relay 26 with a' heating coil between which carries at its movable end a switch contact 46 which normally connects the spring jaws 47 in the circuit of magnet 32. The'spring 48 is provided which normally tends to retract the armature 4l from con-A operation, the parts are in the position.

shown in Fig. l. At this time the current in the right hand phase passes through switch blade 13 and heating resistance coil 28. The other side of this phase passes through blade 14 to terminal 10. The magnet coil 82 and the thermostatic switch member 8O are normally in circuit across this phase, the switch 46, 47 being held closed by the energized magnet coil 40. At this time the magnet Coil 32 holds the armature 34 and the rod 35, crank 23 and all the switch blades in a closed circuit position. It the conditions in the left hand phase are normal, the circuit through the relay 27 is closed and the magnet coil 4() is holding the supplementary switch 46, 47 closed. Should the 'voltage decrease in the right hand phase, the magnet coil 82 will release the armature 33, and the spring 25 will throw the crank 23 and open the circuits through both phases. Should the voltage in the left hand ,phase fall below a predetermined amount the magnet coil 40 will release its armature 4l and the spring 4S will throw .the arm 45 outward and Open the circuit between contacts 46 and 47, thus doenergizing the magnet coil 32 and acting to throw the main switch in the same way that a decrease in the voltage of 'the right hand phase .would do.

Should the load ot the right hand phase increase above a predetermined amount the heat from the coil 28 would warp the thermostatic switch element 3Q in the relay 26 away fronrthe contact 3l and open the circuit of the magnet 32, thus releasing its armature and opening the switch as before. Should the load in the lett hand phase be increased above a predetermined amount, the thermostatic element et' the relay 27 would open the circuit through the coil 4t) and release supplementary switch 46, 47 and open the circuit as above described.

According lo my invention, the two magnets 32 and 40 are alike except that one has a slide and 'hinged connection with thc operating crank 29, while the other operates the supplementary switch which is in circuit with the first. Y

`I claim:

l. An enclosed switch comprising four movable switch members, a hand operable crank therefor, a spring tending to move said switch to open circuit. position, an electro-magnet in shunt with two of said switch members for holding all of said members in a closed circuit position, a supplemental switch in circuit with said magnet,-

a second electro magnet connected in shunt with the other two switch members for controlling said supplemental switch, an overload-relay in series with each of two of said switch members, each relay ha'ving a heating element and a thermostatic member adapted to automatically open the circuits through one of said electro magnets. I

,2. vIn an electric switch, the combination of two pairs of switch blades with appurtenant circuit terminals, quick-break mecha.- nism connected to all of said blades for simultaneously operating them to open the cir'- l cuits, an electro-magnet in shunt relationship to the blades of one pair of said blades for holding the quick-break mechanism in closed circuit position under normal conditions, an electro-magnet in shunt relationship to the blades of the other pair of blades, an

auxiliary switch in series with the first mentioned magnet and 'controlled by the second magnet, and a thermostatic switch member inseries with one of the blades of each pair of blades, and a base serving as a mounting for all of vsaid parts. I

3. An electric switch construction including a main switch having four movable blades land appurtenant contacts, manualmeans for operating said switch, a main magnet in shunt relation with two of said blades for holding said switch in closed position while the voltage is substantially normal, an auxiliary switch having contacts in circuit with said main magnet, an auxiliary magnet in shunt relation with vthe other two blades for holding said auxiliary Iswitch in closed circuit position while the BENJAMIN E. GETCHELL.

predetermined decrease in voltage in the circuit. 

